The present invention relates to chimeric and humanized anti-idiotype antibodies that specifically bind carcinoembryonic antigen antibodies. The invention further relates to the uses of the chimeric and humanized anti-idiotype antibodies as clearing agents in therapeutic methods, as a vaccine, and to detect in biological fluid samples the presence of an antibody or fragment thereof that specifically binds CEA.
The use of targeting monoclonal antibodies conjugated to radionuclides or other cytotoxic agents offers the possibility of delivering such agents directly to the tumor site, thereby limiting the exposure of normal tissues to toxic agents. (Goldenberg, Semin. Nucl. Med., 19:332 (1989)). In recent years, the potential of antibody-based therapy and its accuracy in the localization of tumor-associated antigens have been demonstrated both in the laboratory and clinical studies (see., e.g., Thorpe, TIBTECH, 11:42 (1993); Goldenberg, Scientific American, Science and Medicine, 1:64 (1994); Baldwin et al., U.S. Pat. Nos. 4,925,922 and 4,916,213; Young, U.S. Pat. No. 4,918,163; U.S. Pat. No. 5,204,095; Irie et al., U.S. Pat. No. 5,196,337; Hellstrom et al., U.S. Pat. Nos. 5,134,075 and 5,171,665). In general, the use of radiolabeled antibodies or antibody fragments against tumor-associated markers for localization of tumors has been more successful than for therapy, in part because antibody uptake by the tumor is generally low, ranging from only 0.01% to 0.001% of the total dose injected (Vaughan et al., Brit. J. Radiol., 60:567 (1987)). Increasing the concentration of the radiolabel to increase the dosage to the tumor is counterproductive generally as this also increases exposure of healthy tissue to radioactivity.
Carcinoembryonic antigen (CEA) is a 180,000-Da glycoprotein expressed in most adenocarcinomas of endodermal-derived digestive-system epithelia and in some other types of cancer such as breast cancer and non-small-cell lung cancer. One of the main advantages of the CEA system is that AB1 anti-CEA have been extensively used as radioimmunodetection agents in cancer patients. One such antibody, MN-14, is a murine IgG1K monoclonal antibody (Mab) with high affinity (KD=10xe2x88x929M) for human CEA. In cancer patients, 131I-MN-14 targets CEA-producing tumors effectively, and radiolabled MN-14-Fabxe2x80x2 can detect lesions as small as 2 cm in diameter.
Rat anti-idiotype antibody (rWI2) against an anti-carcinoembryonic antigen antibody (MN-14) has been considered as a potential idiotype vaccine, capable of eliciting an Ab3 response in immunized animals. Losman et al., Int. J. Cancer 56:580-584 (1994). It has also been shown that WI2 can serve as an effective clearing agent improving tumor/nontumor ratios and reducing myelotoxicity, when used to remove excess radiolabeled MN-14, as shown, for example, in U.S. Pat. No. 4,624,846, the entire contents of which are incorporated herein by reference. However, its use is limited by the short biological half life of the rat Ab, due to rejection by the human host.
It is an object of the present invention to provide a chimeric anti-idiotype Ab with anti carcinoembryonic-antibody properties, a humanized anti-idiotype Ab with anti carcinoembryonic-antibody properties as an immunological reagent useful in clearing an organism of anti-CEA antibody initially used as a cancer treatment, diagnostic, or vaccine, where the anti-idiotype Ab has the immunogenic properties of a human MAb in a human patient, and to provide an anti-idiotype Ab with anti carcinoembryonic-antibody properties which can serve as a detection agent or vaccine. It is another object of the present invention to provide DNA constructs encoding such antibodies.
To achieve these objectives, in one aspect of the invention, a chimeric anti-idiotype antibody or fragment thereof which specifically binds to the idiotype region of an anti-CEA monoclonal antibody is provided, comprising the rWI2 light chain and heavy chain variable regions, or silent mutations thereof. In a preferred embodiment, the heavy chain variable region comprises the ratWI2VK sequence (SEQ ID NO:18) shown in FIG. 1 and the light chain variable region comprises the RatWI2VK sequence (SEQ ID NO:22) shown in FIG. 2.
In another aspect of the invention, a humanized anti-idiotype antibody or fragment thereof which specifically binds the idiotype region of an anti-CEA monoclonal antibody is provided, comprising rWI2 CDR regions and humanized FR regions. In a preferred embodiment, the heavy chain variable region comprises the KOLWI2VH-1 or the KOLWI2VH-2 sequence (SEQ ID NOS:19 or 20 respectively) shown in FIG. 1 and the light chain variable region comprises the REIWI2VK or the REIWI2VKRS sequence (SEQ ID NOS:22 or 23 respectively) shown in FIG. 2.
In another aspect of the invention, an isolated polynucleotide encoding the heavy chain or the heavy chain variable region of a chimeric or humanized antibody or antibody fragment which specifically binds the idiotype region of an anti-CEA monoclonal antibody is provided, comprising sequences encoding at least two rWI2 heavy chain CDRs, selected from the group of CDRs consisting of:
the complementary determining region -1 (CDR-1) sequence (SEQ ID NO:1) NYWMT,
the complementary determining region -2 (CDR-2) sequence SITSTGGTYHAESVKG, (SEQ ID NO:2) and
the complementary determining region -3 (CDR-3) sequence DDYGGQSTYVMDA (SEQ ID NO:3).
In another aspect of the invention, an isolated polynucleotide encoding the light chain or the light chain variable region of a chimeric or humanized antibody or antibody fragment which specifically binds the idiotype region of an anti-CEA monoclonal antibody is provided, comprising sequences encoding at least two rWI2 CDRs, selected from the group of CDRs consisting of:
the complementary determining region -1 (CDR1) sequence RASQDIGNYLR (SEQ ID NO:4),
the complementary determining region -2 (CDR2) sequence GATNLAA (SEQ ID NO:5), and
the complementary determining region -3 (CDR3) sequence LHHSEYPYT (SEQ IS NO:6).
In another aspect of the invention, an isolated first expression vector comprising a gene for the chimeric WI2 heavy chain and an isolated second expression vector comprising a gene for the chimeric WI2 light chain are provided.
In another aspect of the invention, an isolated first expression vector comprising a gene for a humanized WI2 heavy chain and an isolated second expression vector comprising a gene for a humanized WI2 light chain are provided.
In another aspect of the invention, a host is provided, comprising an isolated first vector comprising a gene for the chimeric WI2 heavy chain and an isolated second expression vector comprising a gene for the chimeric WI2 light chain, or an isolated first expression vector comprising a gene for a humanized WI2 heavy chain and an isolated second expression vector comprising a gene for a humanized WI2 light chain.
In another aspect of the invention, a method of stimulating an immune response in a patient against cancers expressing carcinoembryonic antigen is provided, which comprises administering to a patient an effective amount of a vaccine comprising a humanized anti-idiotype antibody or fragment which specifically binds the idiotype region of an anti-CEA monoclonal antibody, conjugated to a soluble immunogenic carrier protein, optionally in combination with a pharmaceutically acceptable vaccine adjuvant.
In another aspect of the invention, a method of diagnosis or treatment of a patient is provided, wherein an antibody or antibody fragment that specifically binds CEA is used as a targeting, pre-targeting or therapy agent, either as such or as a component of a conjugate, the improvement to the method consisting of an anti-idiotype antibody used to clear non-targeted antibody or antibody fragment.
In another aspect of the invention, a method of detecting the presence of an antibody or fragment that specifically binds CEA, in a fluid biological sample, comprising contacting the sample with rWI2, or a chimeric anti-idiotype antibody or antibody fragment which specifically binds the idiotype region of an anti-CEA monoclonal antibody, or a humanized anti-idiotype antibody or antibody fragment which specifically binds the idiotype region of an anti-CEA monoclonal antibody, and detecting binding of said anti-idiotype antibody or antibody fragment to an antibody idiotype or antibody idiotype fragment in said sample.